Studies are proposed to determine the properties of the ligaments, disks, and vertebral bodies of the human cervical spine in axial and eccentric compression, axial rotation and tension. Tension studies will be done on individual ligaments and disks in situ. All supporting tissue, except the element under study, will be eliminated at each spinal level. Similarly, the disks and vertebral bodies will be evaluated in compression and rotation. All the experiments will be done at 1 and 500 cm/s. Additionally, load relaxation studies and evaluations of intact cervical functional units will be conducted. Because the dimensions of the ligaments are difficult to determine in situ, selected cadavers will be sectioned using a cryomicrotome to visualize the cross-sectional anatomy. Photographs of the cross-sections will be digitized to determine the cross-sectional areas. The ultimate forces, deflection stresses and strains will be determined along with stiffness and elastic modulus for each element.